Semi-automatic telephone system.



. M. SCHWARTZ;

SEMI-AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED DEC. 2, 1911, RENEWED NOV. 9,--1914.

Patented July 20, 1915;

3 SHEETS-SHEET 1.

WITNESSES mum/70R:

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BEST" AVAILABLE copy M. SCHWARTZ; SEMI-AUTOMATIC TELEPHONE SYSTEM. APPLICATION- FILED DEC. 2,1911. RENEWED NOV. 9.1914.

1,146,821. w 'PatentedJuly. 20,1915.

3 $HEET S-SHE ET 2.

WITNESSES M., SCHWARTZ. SEMI-AUTOMATIC. TELEPHONE SYSTEM. A PPucA'noN FILED DEC. 21 1911. RENEWED NOV. 9. 1914.

1,146,821. I E ,PatntedJu1 20J915 s SHEETS-SHEET 3.

MENTOR?- IQfi q E, a sfi fliamiii lines are all carried through a special B-op- UN HTED STATES P MICHAEL SCKWABTZ, OF CHICAGO, ILLINOIS, ASSIGNC'R T0 AU'EQMATIEG ELECTRZG UOMLPANY, OF CHICAGO, ILLINOIS, A. COB-PflR'ATITQN 3F ILLINGIS.

SEMI-AUTOMATIC TELEPHQNE S'STSTELHC.

Specification of Letters Patent.

Paton ted d nly ac, 1%15.

Application filed December 2, 1911, Serial no. 663,567. Renewed November 9, 1914-. Serial No. SZLZOO.

To all 1.0/1 (Hit it may concern Be it known that I, Micimnn Sonwan'rz, a citizen of the United States of America, and resident of Chicago, Cook county, lllinois, have invented a certain new and useful Improvement in Semi-Automatic Telephone Systems, of which the following is a specification.

My invention relates to automatic telephone systems, and especially to an imtiple jack at each operators position. On

account of the added expense and the 001m plication of the duties of the operators, an automatic calling device is not provided at ach operators position. Instead, the trunk erators position. This position is provided with supervisory lamps tor the trunks, one or more calling devices, and a key in each trunk by means of which the calling device may be connected with the trunk.

The method of making the call in such a system is as follows: The A-operator, upon receiving an order for connection with the automatic exchange, connects with an order wire and repeats the number of the line wanted to the Boperator. T he B-operator then assigns an idle trunk line to the Aoperator, all the busy trunks usually being disclosed to the B-operator by means of a lamp which lights whenever the trunk is in use. After assigning the trunk, the .B-OPGIMLOP then operates the calling device key of the trunk assigned and operates the calling device for the called number.

In my improved system the general arrangement of the system and the operations of the A-"perator are substantially the same as described above. At the B-operators position,lghowever, the trunk equipment is simplifieq and the operations required of the Bope'rator lessened. There are r keys in the trunks at the B-operatofis position, the only apparatus appearing before the B- operator being two lamps for each trunk and a calling device. One of these lamps is always displayed on the B-operators position, this lamp belonging to an. idle trunk and designates which trunk the B-operator shall next assign to the A-operator. When the B-operator receives an order she merely looks to see which lamp is displayed, assigns the corresponding trunkand then begins to operate the calling device. This calling device is always automatically connected with the trunk line Whose light is displayed, and as soon as the last digit'is called the calling device is automatically disconnected from the trunk whose light is displayed and automatically connected with the next idle trunk, and the lamp associated with this last-mentioned trunkis displayed. The second lamp belonging to each trunk is displayed when the A-operator connects with the designated trunk, in order'to notify the B-operator when the A-operator has made such a connection. This lamp is not lighted in case the A-operator should plug in upon the wrong trunk.

A further object of my invention is to provide improved means for selectively signaling on a party-line. I-leretofore it has been customary to connect each line with a plurality of groupsofconneetors, or to use a frequency selector of some sort in combination with the selector switches. Other systems have been proposed in which each line is connected with a plurality of contacts 1n diderent levels oi the same switch, and auxiliary wipers are employed by means of which one generator is connected if it is called over its contacts situated in one level, while a different ringing current will be useir- 1f the line is called over its contacts 1n second level. In my improved system, however, I provide a connector .are likewise used. The two sets of wipers the contacts of this called line.

i the line.

-station corresponding to the second ringing are adapted to engage the same bank level,

but are angularly displaced so thatthe second set does not pass onto the first contact until the first set passes off the last contact. when the ringing relays are energized, on.e generator is connected with one set of wipers, while the other generator is con nected with the other set. In this manner the frequency of the ringing current which 'will be sentout on a called line'depends generator, the shaft would be rotated fifteen steps so as-to bring the second set of wipers onto the line. In order to rotate the shaft fifteen steps, the calling device is operated first for O, for which ten impulses are transmitted, and then 5.. Thissecond rotation is ence to the accompanying drawings type.

made possible by the provision of means for closing the circuit of the private. magnet and locking the side switch in second position when the switch shaft is rotated the tenth step, so that the rotary magnet is operative to continue the rotation in accordance with the next series of impulses.

These and other objects of my invention will be more readily understood by referwhich- Figures 1, .2 and 3 show a complete connection between a calling and a called substation in a system embodying the principles of my invention. The connection shown is established between a calling manual substation A and a called automatic substation A. This connection is established through the medium of an operators cord circuit C, an automatic selector switch D and a connector E. The manual substation A may be of any suitable common battery At the central oiiice the manual line is provided with the usual answering jack 3 1e or more multiplejacirs J, the line relay 2, the cutoff -relay 3 and the line lamp 4. The operators cord'G is a cord which is adapted for use either with manual lines or with trunk lines leading to the automatic exchange. This cord comprises the usual plugs P and P connected together through the condensers 5 and 6. he cord is provided with ,two double-wound polarized relays 7 and 8 and two auxiliary relays 9 and 10. The armatures of the polarized 'relays return to central position when the relays are deenergized, from which position they may be attracted to either side, depending upon which direction the current flows through the windings. When the relays 9" and 10 are deenergized, the supervisory circuits of the cord are adapted for use in; connection with automatic lines. In order to adapt either end of the cord for use with a manual line the corresponding relay S} or 10 must be energized.

The trunk line leading from the manual necting an automatic calling device with the .trunk. This calling device is situated upon a special or B-operators position. At-this B-operators position there are also two supervisorylamps 12 and 13 (Fig. 2) for the trunk. The lamps 14 and 15. are similar lamps for a second trunk. For controlling the supervisory lamps and the connection of the calling-device with the trunks, there are provided two mechanisms L and M which are common to a plurality of trunk lines. The device L comprises any suitable ratchet device, such as the wheel 16, which is adapted to permit the springs 17 to open when the magnet 18 is energized once, and

to close the springs 19 after the magnet 18 has been energized a predetermined number of times. The number of stepsof the wheel required to close the springs 19 should be equal to the number of digits in the numbers of the automatic lines. The magnet 20, when energized, withdraws the retaining pawl from the ratchet wheel and allows it toreturn to normal posit ion. The mechanism M comprises a set of wipers 21, 22, 23 and 24- carried upon a rotary shaft controlled by a motor magnet 25. Each wiper moves over and makes contact with a set of contacts, one contact for each trunk line.

The contacts engaged by the wiper 21 are connected with the lamps 13, 15, etc. The contacts engaged by the wiper 23 are 0011- nected with the relays 11 of the respective trunk lines. The wiper 22 engages a double set of contacts, one set being connected with the lamps 12, 14, etc, and the other set being connected with the spring 26 of the respective trunk. Only the last contact of the set engaged by the wiper 21 is used, this contact being connected with the springs 26 of the last trunk line of the group. A magnet 32 is provided which, when energized, withdraws the retaining pawl from the shaft which carries the wipers21, 22, 23 and 24, and allows them to be returned into engagement with first contacts. Associated with the device M there are also 'two: relays 27 and 28. The relay 28 is slowl acting that is, slot: to deenergize. i

The automatic'calling device may be of any suitable type and is represented in Fig.

2 by a pair of impulse'springs 29Za'nd 30. Such calling devices are usually controlled by a dial provided with finger holes. The

calling device is alsoprovided with a pair of. springs 31 which are closed once each time the calling device is operated. If the calling device is controlled by a. dial, the springs 31 may be arranged to close as soon 'as the dial is rotated from normal position and open again when the dial returns to normal position after all the impulses are delivered- The key K is located on the B- operators position and is common to all the trunk lines. The selector D is of the general type disclosed in United States Letters Patent No. 815,321, granted March 13, 1906, to Keith, Erickson and Erickson, being modified, however, as shown in British patent to T. G. Martin, No. 1419 of 1910, in order to operate in a two-wire systemthat is, a

comprising the wipers, 39, 40, 41 and42 is controlled by the private magnet 43 in a manner well known in the art. 1 "Means for restoring the switch to normal position are provided in the release magnet 44. This magnet restores the switch immediately upon energizing, in a manner similar to that shown in United States Letters Patent No. 815,176, granted March 13, 1906, to Keith, Erickson and Erickson, for connector switches, rather than by dee'nergiZ-ing as-shown in said selector patent. The relays 45, 46 and 47 are slow acting relaysthat is, relays which denergize slowly after their energizing circuits are broken. The proper action of these relays may be obtained by placing a ring of copper around one end of the core. The connector E is of the general type shown in said Patent No. 815,176 referred to above. Like the selector switches, the connector switch comprises a bank of contacts which are adapted to be engaged by a set of wipers carried upon avertically and rotatably movable shaft. Instead of the usual single set of line and privafe wipers, the connector E is provided with ,a double set of wipers 48, 49 and 50, and 51, 52 and 53. The wipers 51, 52 and 53 a -e arrange in the same plane as the wipers =48, 49 and 50, but are angularly displaced therefrcm a proper distance so that as the Wipers 51, 52 and 53 pass off the last contact of any cer- 'tain level, the wipers 48, 49 and 50 will pass onto the first contact. For instance, assuming the usual arrangement of ten contacts in a level, the wipers would be so arranged that upon the eleventh step of the shaft the wipers 51, 52 and 53 would pass ofi' the tenth contact and the wipers48, 49 and 50 would be rotated onto the first contact of the same level. The Wipers 51 and 52 are insulated from the wipers 48 and 49. These two pairs of wipers are normally connected in multi-- ple with each other and with the talking circuit conductors or line through the springs of two ringing relays 54 and 55. However, when the relays 54 and 55 are energized, these wipers are disconnected from each other and from the line, and the wipers 51 and 52 are connected with the terminals of the ringing current generator R while, at the same time, the wipers 48 and 49 are connected with the terminals of the ringing current generator R. The two private wipers 50 and 53 are permanently connected together. Upon the switch shaft there is a cam 57 which forces the springs 58 into contact when the shaft is rotated a suflicient dis tance to bring the most advanced set of wipers into contact with the last contact of a levelthat is, assuming ten contacts in a level, thesprings '58 would be closed upon the tenth rotary step of the shaft, but would be opened again as soon as the shaft takes the eleventh step. For simplicity, the level of bank contacts shown in Fig. 2 comprises only three contacts. However, in the description which follows the usual arrangement of ten contacts in a level will be assumed.

The automatic substation A is assumed to -be one station of a two-party line, a second tion A being adapted to be connected to the terminals of said line; but if the wipers are rotated eleven steps instead of one, the wipers 48 and 49 will be brought into contact with said line, As has been explained, the wipers 48 and 49 are supplied with ringing current from the generator R, while the Wipers 51 and 52 are supplied with ringing current from the generator R. The generator R is assumed to furnish ringing current of the proper character to operate the ringer at the substation A only, While the generator R furnishes ringing current of the proper character to operate the bells of the other substation on the line. \Tlierefor,

it will be seen that the subst-afircns may be 1 signaled selectively, depending uponwhich pair of wipers is in engagement with the bank contacts of said line. The numbers of thetwo substations on a line will be the same, except that one substation will have a O inserted between the last and the next to the last digits of the number of the other substation on the same line. For instance, the number of substation A being assumed to be 2201, the number of the other substation on the same line would be 221. The automatic substation A may be of any suitable type and, as herein represented, comprises the usual receiver 61, transmitter 62, switch hook 63, ringer 64L, condenser 65 and an automaticcalling device com rising a pair of impulse springs 66 and 6 and the toothed impulse wheel 68, which latter is controlled through the medium of a dial (not shown) provided with finger holes. The line of substation A is shown connected to an individual line switch F at the central office, which line-switch is controlled by a master switch H. The line switch F and master switch H, as shown, are of the general type disclosed in British patent to R. W. James, No. 26,301 of 1906, but of the particular form shown iii-British Patent No. 1419 of 1910 above referred to.

. Having given a general description of the apparatus shown, it will now be explained in detail how the manual substation A may obtain connection with and selectively signal the substation A upon an automatic party-line. The subscriber at substation A, by removing his receiver, closes the circuit of the line relay 2, which, upon energizing, closes the circuit of the line lamp 4 in the usual manner to signal the operator. The operator thereupon inserts the plug P into the jack J, whereupon the subscribers line is connected with the cord circuit C and a circuit is closedfrom ground G through the relay 9, sleeve conductors of the plug P and ac J and the cut-off relay 3 to the battery lead 70, thence to battery B and to ground G.

' It will be understood that although only one battery B is shown in the drawings, a plurality of batteries may be employed if found desirable. or necessary. The relay 3, upon energizing, disconnects the line relay from the calling line. The relay 9, upon energizing, connects the non-grounded terminal of the battery with the upper winding of the relay 8 and ground G with the lower winding of said relay, and also completes a connection frpm the lamp 71 to-the spring 72 of the relay 8. The insertion of the battery between the two windings of the relay 8 provides the calling substation with talking current which flows over a circuit extending from ground G through the armature 74, lower WiT'ding of the relay 8, thence over the heavy 'nqnductors to and through the substation-Aland back overth'e other side of the line through the upper winding ofthe relay 8 and the armature T5 to the battery lead 7 O. This current also energizes the re lay 8 and in the proper direction to separate stores the key K and presses the button K thereby connecting her talking set with an order wire leading to the B-operator. The A-operator then repeats the number of the substation desired to the B-operator and asks to be assigned an idle trunk line over which to complete the connection. The B- operator then assigns an idle trunk line to the A-operator and also operates hercalling device to set up the desired automatic connection.

The only operation required of the A-opcrater after being assigned an idle trunk line is to plug into the trunk line assigned by the B-operator. The B-eperator deter mines which trunk line is to be assigned by means of the lamps 13-15,-etc. (Fig. 2.) The trunk line shown in the drawings is the one corresponding to the first set of contacts in the apparatus in: (Fig. 2), and it. will be assumed that at the time the call was made the wipers were resting upon these contacts. In this position, it will be seen that a circuit is closed from ground G through the springs 104: and 17, wiper 2 L, contact 105* and lamp 1-3 to the battery lead' 70. A circuit is also closed from ground G through the springs 105, 106, 107, wiper 23, contact 108, conductor 79 and the relay 11 to the battery lead. The relay 11 being energized, the calling device springs 29 and 30 -(Fig."2) will be connected with the trunk conductors 82. and 83 leading to the selector D. Thus it will be seen that normally the calling device). is connected with an idle trunk line, and that the corresponding lamp in tlie B-operators position is lighted. The B-operator assigns the trunk corresponding to the lamp which is burning, and then simply begins to operate the calling device for the successive digits of the number desired. It will be assumed that the number of the substation A is 2201. Since the operators calling device is normally bridged across the trunk conductors S2 and 83, the selector line relay his is energized over a circuit extending from ground G through the lower 39, trunk conductor 83, armature 86,,conductor 81, springs ,87, impulse springs 29 and d0, conductor 80, armature 88, con uctor 82, side switch wiper l0 and; the/ upperwinding'of the relay 84 to battery. The re- Upon learning that a line of the autowinding of the relay 84, side switch wiper lay 84-, upon energizing, completes a circuit v extending from ground G"? through the springs 89 and 90 and the relay 45 to bat tery. Now, when the operator operates her calling device for the first digit 2, the impulse springs 29 and 30 are separated twice momentarily, each time breaking the circuit of the selector line relay 84. The relay 45,

' being slow acting, does not have time to deis energized by the first impulse, but, being a slowacting relay, does not decnergize until after the last impulse is delivered. In its energized position the relay46 closes a circuit from ground G through the private magnet 43 to battery. The private magnet 43, upon energizing and dei nergizing, causes the side switch to pass from first to second position after the vertical magnet has operated the last time. (in passing to second position the side switch wiper 41 closes a circuit from ground G through the interrupter springs 93, rotary magnet 38, relay 47 and side switch wiper 41 to battery. Since this circuit includes the interrupter springs 93, the rotary magnet 38 will operate continuously in a manner similar to that of a buzzer to rotate the 'ipers step by step as long as the side switch remains in second position.

If he first trunl: line is idle, the side switch will-be tripped from first to second position by the operation of the armature of the private magnet, in the well-known manner, soon as the wipers have been rotated the first step. If, however, the first trunk line is busy, the private wiper 36 finds a guarding ground potential upon the private bank contact of said trunk line, and a locking circuit is closed from said grounded contact through the wiper 86, side switch wiper 42 and private magnet 43 to battery. The private magnet, being locked up, holds the side switch. in second position, and the rotary magnet continues to advance the wipers until an idle trunk is found. X hen the wiper 36 passescfi the last grounded contact, the private magnet 43 deiinergizes and allows the side switch to pass to third position. Upon passing from second to third position, the side switch breaks the circuit of the rotary magnet, disconnects the line relay 84 from the line and extends the line connection through the wipers 34 and 35 to the connector E. The connector line relay 94 thereupon energized over a circuit extending from ground G through the lower windingof said relay, springs 95 and 96, conductor 97, wiper 35, thence to and through the operators calling device and back over the other side of the line to the springs 9'7 and 98 and the upper winding of the relay 94 to battery. The relay 94, upon energizing, closes thecircuit of the relay 99. The relay 99, upon energizing, extends a guarding potential from ound G through the springs 100 to the selector private bank contacts of the trunk line leading to the connector E. A holding circuit also extends from ground G through the springs 100, selector private wiper 36, side switch wiper 42, springs 101 and 102 and relay 45 of the selector tobattery. A short time elapses between the time when the side switch of the selector D passes to third position and the time when the relay 99 of the connector energizes to extend the guarding potential from ground G- to the selector private bank contacts. During this time said contacts are provided with a guarding potential extending from ground G through the springs 103 and 101 of the relay 4? of the selector D and side switch wiper 42. The relay 47 is energized in series with the rotary magnet and, being slow acting, remains energized for an instant after the side switch passes to third position, but de'e'nergizes soon enough to permit the locking circuit to be closed throughthe relay 4-5 before it has time to deiinergize.

As has been explained, the springs 31 associa ted with the operators calling device are closed into contact once each time the calling device is operated. These springs,

upon closing, complete a circuit from ground G through said springs and the magnet 18 to the battery lead'70. The magnet 18, upon energizing, rotates the ratchet wheel 16 one step, whereby the springs 17 are permitted to separate, thereby breaking the circuit of the lamp 13. The operator now operates her calling device for the second digit 2, thereby causing the line relay of the connector E to deenergize twice. Each time the relay 94 deen'ergizes', a circuit is closed from ground G through the springs 10S and 109, 110 and 111 (the relay 99 is slow acting), relay 112, vertical magnet 113 and side switch wiper 114 to the battery lead. The vertical magnet receiving two impulses operates to raise the wipers two steps to a position opposite the second level of bank contacts.

The relay 112, which is included in the operating circuit of the ,ver-

magnet. The private magnet, upon energizing and deenergizing, causes the side switch to pass from first to second position. The ratchet wheel 16 of the apparatusL is rotated a second step when. the second digit is called, but has no particular effect.

\Vhcn the calling device is operated for the third digit 0, the line relay of the connector is deencrgized ten times in the same manner as for the previous digits, but, since the side switch is in second position, the deenergization of the relay 94 at this time completes a circuit from ground G through the springs 108, 109, 1.10 and 111, relay 112, springs 117, rotary magnet 118 and side switch wiper 114 to battery. The rotary magnet operates ten times to rotate the shaft and wipers ten steps, thereby carrying the wipers 51, and 53 onto the tenth contact of the second level, and at the same time the cam 57 on. the shaft closes the springs 58. The slow acting relay 112 is energized in series with the rotary magnet by the operating impulses and,being slow acting, does not deenergize until after the last impulse is .delivered. Since the digit called was 0, and the springs 58 are closed, the private magnet 116 does not det nergize when the relay 112 deenergizes, but remains'energized over a circuit extending from ground G through the springs 58 and said magnet to battery. Since the private magnet does not denergize after this digit is called, the side switch does not pass to third position, as it would do in case any other digit except 0 had been called, so as not to close the springs 58. The operator now operates the calling device once more for the last digit 1, the line relay deenergizing once, and again closes the circuit of the rotary magnet previously traced. This operation of the rotary magnet advances the wipers one more step, carrying the wipers 51, 52 and 53 oil the last contact and advancing the wipers 48, 49 and onto the first contact of the second level. This last step of the-switch shaft alsopermits the springs 58 to open, so that when the rela- 112 deenergizes after th1s (11 11 is called, the private magnet 116 deenergizes also and permits the side switch to pass to third position. The side switch wipers 119 and 120, upon reaching third position, extend the line connection through the con nector and its wipers and 49 to the called line. The side switch wiper 121, upon reaching third position, extends a guarding potential from ground G through said Wiper and private wiper 50 to the connector private bank contacts of the called line. An energizing circuit also extends from ground G through the wipers 121 and 50, conductor 122 and the cut-oil winding of the switch 1* (Fig. 3:) to battery. The winding 123, upon energizing, attracts the armature 124, which disconnects the switch F from the wipers springs 131, 132 and 133 to battery.

upon energizing, disconnect the calling and r the called-lines and connect the ringing current generators R and R with the wipers 48 and 49 and 51 and 52. Since only the wipers 48 and 49 are in connection with the called. line, ringing current from the genera tor it only will be sent over the line. This current is assumed to be of the proper char acter to operate the bells' at the substation A. If the number 221 had been called, the 51 and 52 would have been connected with the line and ringing current from the generator It would have been supplied to the line, which current, it is assumed, does not operate the bells 64 at the substation A, but would ring thebells of the other substation on the .line.

\Vhen the ratchet wheel 16 of the device L is rotated the fourth step by the operation of the calling device for the last digit of the called number, the springs 19 are closed into contact. Therefore, when the magnet 18 deenergizes after this digit is called, a circuit is closed from ground Gr through the springs 19 and 127 and the relay 27 to the battery lead. The relay 27, upon energizing, completes a circuit from ground G through springs 105, 106, 175 and 176, magnet 25, The magnet 25, upon energizing, rotates the wipers 21, 22, 23 and 24 one step onto the contacts corresponding to the next trunk line. The relay 27, upon energizing, also completes the circuit of the restoring magnet 20 of the device L, said lrcuit extending from ground G through the springs 105, 106 and 170 and the magnet 20 to battery. The magnet 20, upon energizing, withdraws the retaining pawl from the ratchet wheel 16 and allows it to be restored to normal. thereby disconnecting the ground G from the relay 27. If the next trunk is idle, the relay 27 deenergizes and breaks the circuits of the magnets 20 and 25. If the next trunk is busy, however, the relay 27 remains energized and causes the magnet 25 to continue to rotate the wipers 21, 22, and 24 step by step onto the contactsof an idle trunk in the following manner: It willbe seen that the outer set of contacts which are engaged by the wiper 22 are connected to the springs 26 of the jacks of the trunk lines, so that wheir over a. plug in a jack of any trunk line, its

contact in this set will be grounded. Therefore, it the second trunk line is busy when the wipers of the device M are rotated the first step, a locking circuit will be closed from the grounded contact of said trunk through the wiper 22 and the springs 129 and 128 and the relay 27 to battery. Thus,

the relay 27 will remain locked up and the magnet 25 will continue to advance the wipers 21, 22, 23 and 24 until the contacts of an idle trunk line are reached.

In the drawings it has been assumed that the secondtrunk line was not busy, and.

therefore the wipers are shown as having .oome to rest upon the contacts of said trunk.

the calling device from the trunk line and completes the connection between the cord circuit and the trunk. When the relay 11 deenergizes to disconnect the calling device from the trunk, it must close a bridge across the trunk at some other 'point so as to prevent the automatic connection from being released. This bridge comprises the two windings of the relay 7 of the cord circuit C. It will therefore be seen that it is necessary that the A- operator plug into the jack before the B- operator completes the connection. .Tn'order to notify the B-operator when the A-operator plugs in, the lamps 12 and 14 are pro vided. When the plug P is inserted into the jack J a circuit is closed from ground G" through the springs 26, conductor 130, contact point 78, wiper 22, contact point 77 and lamp 12 to battery. Since this circuit includes the wiper 22, it will-be seen that neither the lamp 12 nor any other similar lamp will be lighted if the A-operator plugs into the wrong trunk line. The lamp 141 (Fig. 2) is energized in multiple with the magnet, 25 for the purpose of signify ing to the B-operator when the device M isoperating. The key K is for the purpose of providing means whereby the B-operator may release a partially established connection in case she finds she has made a nistake in the operation of the calling device. The separation of the springs 87 by the operation of the key opens the bridge across the trunk line through-the calling device, and permits the automatic switches to be released. The clo sure of the springs 142 closes the circuit of the magnet 20 to allow the device L to be returned to normal position. v

If it is desired to put any set of trunks out of service, the key K may be operated to open the springs 104 and 105, thereby allowing the relay 11' to deenergize and also breaking the circuit of the lamp of the trunk line upon which the wipers 2124. are resting. The wiper 21 is for the purpose of releasing the device M and causing its wipers to i be returned" to normal positlon when they reach the limit of their travel. Only the last contact of the row engaged by the wiper 21 is used. This contact is connected with the spring 26 of its corresponding trunk line. Therefore, when the wipers are standing upon the contacts of this trunk line and the plug is inserted into the jack, a circuit is closed from ground through the spring 26 and the trunk line, wiper 21, springs 143 of the relay 27 (when it is energized, as previously explained) and the, relay 28 to the .battery lead. The relay 28, upon energizing, breaks the circuit of the magnet 25 and closes the circuit from ground through the restoring magnet 32, springs 144 and 132 and springs 133 to battery. The relay 28 is SlOW acting so asto maintain this circuit closed until the wipers have had time to reach normal position before permitting the magnet 32 to deenergize.

When the relay 7 at the cord 0 is bridged across the line upon the completion of the connection by the B-oper ator, in the manner previously explained, this relay is energized by a current which is supplied to the line through the windings of the line relay 94 of the connector E.

This current is in the proper direction to cause the relay 7 to close the springs 145, thereby completing a circuit through the lamp 146. When the called subscriber removes his receiver, or as soon thereafter as the ringing relay of the connector denergizes, the called substation is provided with talking current over a circuit extending from ground G at the connector E through ing ofthe relay 147 to battery. The relay-147 is energized by this current and, by shifting the springs 96 and 97 out of engagement with their back contacts. into engagement with their front contacts, transposes the connections between the windings of the line relay of theconnector and the two sides of the talking circuit. This transposition r everses the direction of the current in the relav 7 of the cord C. This causes the relay 7 to attract its armature in the opposite direction, thereby opening the springs 145 to extinguish the lamp 146 to signify to the operator that the called subscriber has answered The relay 147 of the connector, upon energizing, also completes a circuit extending from ground G through the side switch wiper 121, springs 157 and the relay 158 to battery. The relay 158, upon energizing, opens the circuit of the ringing relays 55 and 54 at the springs 126 so that the called subscriber will not' be rung again forms a locking circuit for itself through the springs 159, so that it will not deenergize when the called subscriber hangs up the receiver and allows the back'bridge relay 147 to denergize.

When the calling and called subscribers hang up their receivers upon the termination of the conversation, the A-operator is given the usual disconnect signals in the following manner: The hanging up of the.

receiver at the substation A destroys the circuit of the relay 8 in the cord, which, upon deenergizing, permits the springs 72 and 73 to close, thereby extending a circuit from ground G through said springs 7 3 and 72, armature 160 and lamp. 71 to battery. The hanging up of the receiver at the called substation breaks the circuit of the connector back-bridge relay 1-17. The relay 147, upon deenergizing, restores the current in the cord supervisory relay 7 to its original direction, thereby causing the springs 1 15 to be closed again to light the lamp 146. The

A-operator, upon receiving the disconnect signal, simply withdraws the plugs P and P whereupon the automatic connection is automatically released as follows: The removal of the plug P breaks the circuit of the connector line relay 94. The relay 94:, upon deenergizing, breaks the circuit of the relay 99. The rela 99 noon deener izin completes a circuit from ground G through the springs 108 and 109, spring 110 and its back contact, release magnet 161 and ofi'- normal springs 162 to battery, The magnet 161, upon energizing, immediately restores the connector to normal position, and when the switch shaft reaches its lowest position, the springs 169 are separated to permit the magnet 161 to deenergize. The deenergization of the relay'99 also breaks the holding circuit of the release relay 4:") 01": the selector 1). The relay 4-5, upon deiinergizing, closes a circuit from ground G through the spring- 89 and its back contact, spring 92 and its back contact, magnet 4 and off normal springs 16 to battery. The magnet 4&1, upon energizing, releases the selector 1), and the switch shaft breaks the circuit of the re lease ma net 4-1 at the sprin s 164: when it I'D D .not have completed connection therewith,

reaches its lowest position.

In the above description of the operation of the connector switch it was assumed that the called line was idle. If the called line had been busy, the connector switch would because, when the wiper 50 engaged the contacts oi? said busy line and while the side switch. was yet in second position, a. circuit would have been closed from ground through the guarded private bank Contact of the busy line through the private wiper 50, side switch wiper 121 and the lower winding of th elay 165 to battery. The closure of the springs 166 by the energization of the relay 165 completes a circuit from ground Gr through the springs 100, springs 166, upper winding of the relay 165 and the private magnet 116 to battery. The closure of this circuit maintains the private magnet 116 energized after the relay '112 deenergizcs after the last impulse for. thelast digit. is delivered. Since the private magnet does not deenergize, the side switch remains locked in second position and the connection is not completed at the side switch wipers 119 and 120. The .relay 165, upon energizing, also completes a connection from one terminal of the busy signaling machine S through the springs 167, contact point 168, side switch wiper 120 and condenser 169 and thence back through the cord circuit to the calling line, thereby giving the calling subscriber a busy signal. The calling subscriber, upon receiving the busy signal, will hang up his receiver and cause the supervisory lamp 71 at the cord to be lighted. Since the backbridge relay 147 of the connector is deenergized, the relay 7 at the cord will be ener gized in the proper direction to light the lamp 146. Therefore, the two lamps will be lighted simultaneously and the operator will remove the plugs, whereupon the automatic switches '13 and. E will be released in the same manner'as previously described.

In the system shown herein. the numbers of some of the automatic substations have only three digits, while other stations have. four digits. In the device L the springs 19 must not be closed until the last digit of any number is called, and therefore said springs must not be closed until the wheel 16 has been rotated four steps. If a three-digit number is called, the wheel '16 would, of course. be rotated only three steps. In order to cause these springs to be closed when such a number is called, the operator may be instructed to operate the calling device once more after the last digit is called. This last operation of the calling device will have no effect on the automatic switches other'than to momentarily decnergize the line relay of the connector. At the device L, however,

"this operation of the calling device will cause the wheel 16 to be advanced the fourth step to close the springs 19, which is for the purpose of starting the selection of the idle while 1 have described. this connector in con-' nection with a semi-automatic system, it is equally as well adapted for use in any system in which automatic switches are employed. I Y

What I claim as my invention is 1. In a telephone system, a plurality of trunk lines, an impulse transmitting device, and automatic means for maintaining said impulse transmitting device in c nnection with an idle trunk. v y

2. In a telephone system, a plurality of automatic switches, a plurality of trunk lines extending-t0 said switches, an impulse transmitting device for transmitting impulses over said trunks for controlling said switches, and means for maintaining said impulse transmitting'device always in connection with an idle trunk.

3. In a telephone system, a manual operators board, automatic switches, trunk lines extending from said manual board to said switches, an impulse transmitting de= vice for transmitting impulses over said trunks for operating said switches, and automatic means for maintaining said impulse transmitting device always in connection with an idle trunk line.

4. In a telephone system, an Aoperators position and a B-operators position, automatic switches, trunklines extending from said A-operators position through said 13- oper tors position to said automatic sw'. (hes, an impulse transmitting-device at said B-operators position for transmitting impulses over said trunks for operating said switches, and automatic means for-always maintaining said impulse transmitting device in connection with an idle trunk.

5: In a telephone system, a plurality of trunk lines, an impulse transmitting device, automatic means for maintaining said impulsetransmitting device in connection with an idle trunk, and a signal to indicate to which of said trunk lines said impulse transmitting device is connected.

6. In a telephone system, a plurality of automatic switches, a plurality of trunk lines extending to said switches, an impulse transmitting device for transmitting impulses over said trunks for controlling said switches, means for maintaining said impulse transmitting device always in connection with an idle trunk, and a signal to indicate to which of said trunk lines said impulse transmitting device is connected.

7. In a telephone system, a manual operators' board, automatic switches, trunk lines extending from said manual board to said switches, an impulsetransmitting device for transmitting impulses over said trunks for operating said switches, automatic means for maintaining said impulse transmitting device always in connection with an idle trunk line, and a signal to indicate to which of said trunk lines said impulse transmitting device is connected.

8. In a telephone system, an A-operators position and a B-operators position, automatic switches, trunk lines extending from said Aroperators position through said B- operators position to said automatic switches, an impulse transmitting device at said B-o'peratofls position for transmitting impulses over said trunks for operating said switches, automatic means for always maintaining said impulse transmitting de ice in connection with an idle trunk, anda signal to indicate to which of said trunk lines said impulse transmitting device is connected.

9. In a telephone system, a plurality of trunk lines, a calling device normally con nected with one of said trunks, automatic means controllable by said calling device for extending a connection from said trunk line to a called subscriber, and means con trolled by said calling device for automati a cally disconnecting said calling'device 2'1 the trunk line after the call is C(lllIPiCe-fl. and. for connecting it with an idle trunk.

10. In a telephone system, a plurality of subscribers lines, a plurality of automatic switches for extending connection to said subscribers lines, a plurality of trunk lines extending to said switches, an impulse transmitting device normally connected with one of said trunks for controlling said automatic switches, and means for automatically disconnecting said impulse transmitting device from the trunk upon the completion of a call and for then connecting said impulse transmitting device with an idle trunk,

11. In a telephone system, a plurality of subscribers lines, a plurality of automatic switches for extending connection to said subscribers lines, a plurality of trunk lines extending to said switches, an impulse transmitting device normally connected with one of said trunks for controlling said automatic switches, and means controlled by said 1111- pulsc transmitting device for disconnecting said impulse transmitting device from the trunk upon the completion of a call and for then connecting said impulse transmitting device with an idle trunk.

12. In a telephone system, a plurality of subscribers lines, means for extending a connection between any two of said lines, said means including an A-operators position, a B-operators position, automatic switches, trunk lines extending from said A-operators position 'through' said B- operatorsposition to said 'aut omatio switches, an impulse transmitting device normally connected with one of said trunk lines for controlling said automatic switches,

and means for automatically disconnecting said impulse transmitting device from said trunk after the call is completed and for connecting it with an idle trunk.

1-3. In a telephone system, a plurality of subscribers lines, means for extending a connection between any two of said lines, said means including an A-operators position, a B-operators position, automatic switches, trunk lines extending trom said Ai-operators position through said B-operators position to said automatic switches, a'nimpulse transmitting device normally connected with one of said trunk lines for controlling said automatic switches, and means controlled by said impulse transm1t ting device for automatically disconnecting said impulse transmitting device from said trunk after the call is completed and for connecting it with an idle trunk.

14.111 a telephone system, a manual operators board, automatic switches, a plurality of trunk lines extending from said board to said switches, an impulse transmitting device normally connected to one of said trunk lines for controlling said switches, and means for automatlcally disconnecting said impulse transmitting device from the trunk line when the call is completed and for then connecting it with an idle trunk.

15. In a telephone system, a manual operators board, automatic switches, a plural ity of trunk lines extending from said board to said switches, an impulse transmitting device normally connected to one of said trunk lines for controlling said switches, and means controlled by said impulse transmit ting device for automatically disconnecting said impulse transmitting device fromthe trunk line when the Call is completed and for then connect ng it with an ldle trunk.

1.6. In a telephone system, an A-omrators position and a ll-operators position, autolishing a connection between a calling and a called subscriber, and means for disconnecting said c2 lling device from said trunk and. connecting the same with an idle trunk 'wnen said calling device has been operated a predetermined number of times. 7 18,111 a telephonesystem, an operator's cord circuit, automatic switches, trunk lines extending from said cord to saidswitches, an impulse transmitting device normally connected with one of said trunks and adapted to be operated a plurality of times in establishing a connection between a cal-ling and acalled subscriber, and means for disconnecting said impulse transmitting device from said trunk and connecting the same with an idle trunk when saidimpulse transmitting device has been operated a predetel-mined number of times.

19. In a telephone system, an A-operators position and a B=operatorsposition, automatic switches, trunk lines extending from said A-operators position through said B- operators position to said switches, an im- -pulse transmitting device at said B-operators position normally connected with one of said trunks tor controlhng said switches, 331d. impulse transmitting device being adapted to be operated a plurality of times in establishing a connection between a callmg and a called subscriber, and'means for disconnecting said impulse transmitting device from said trunk and connecting the same with an idle trunk when the same has been operated a predetermined number of tlmes. v

20. In a telephone system, a plurality of trunk lines, a calling device, a step-by-step switch for connecting said calling device with one of said trunks, and means for operating,s'aid switch upon the completion of a Call.

21. In a telephone system, an A-operators position and a B-operators position, automatic switches, trunk lines extending from said A-operators position to said switches,

a calling device at said B-operatofs position normally connected. to one of said trunks, a step-by-step switch for controlling the connection of said calling device with said trunk, and means for operating said switch upon the completion of'each' call to connect said calling device with the next idle trunk.

22. In a telephone system, an A-operators position and a B-operatorsposition, automatic switches, trunk lines extending from said A-operators position to said switches, a calling device at said B-operators position normallyconnected to one of said trunks, a stop-by-step switch for controlling the connection of said calling device with said trunk, means for operating said switchupon the completion of each call to connect the calling device with the next idle trunk, and a signal to indicate with which trunk said calling device is connected.

23. In a telephone system, a plurality of trunk lines, a calling device normally con- 'n ected with one of said trunklines, a stepby-stepswitch adapted to control the'connection of said calling device with said trunk lines, said switch including a plurality of arms adapted to contact With-corresponding bank contacts, and means for returning said to the first of said contacts when they come in contact with thelast of said contacts.

24. In a telephone system, an A-operators 1 position and a B-operators position, aut0- matic switches, trunk lines extending-from said A-operators position through said B- operators position to said automatic switches, an. impulse transmitting device at said B- operators position for transmitting impulses over said trunks for operating said switches,

' said B-operators position for transmitting position and a switches, a calling device normally connecta impulses over said trunks for operating said switches, automatic means for always maintaining said impulse transmitting device in connection with an idle trunk, a signal to indicate to which of said trunk lines said impulse transmitting device is connected, and means at said B-operators position for controlling the release'of said switches.

26. In a telephone system, a plurality of subscribers lines, means for extending a a connect on between any two of said lmes, said means including an A-operators position, a' B-operators position," automatic switches, trunk lines extending from said A-operators position through said B-operators position to said automatic switches,

an impulse transmitting device normally connected with one of said trunk lines for controlling said automatic switches, means for automatically disconnecting said impulse transmitting device from said trunk after the call is completed and for connecting it with an idle trunk, and'means at said B-operators position for controlling the release of said switches.

. 27. In a telephone system,'an A-operators B-operators position, automatic switches, trunk lines extending to-said ed with one of said trunk lines; means at said A-operators position for "connectin with said trunk lines, a signal at said -operators position for indicating when said A-operator connects with the trunk with which said calling device is connected, and means at said B-operators position for controlling the release of said switches.

:28. In a telephone system, a connector switch, a plurality of sets of'contact arms for said switch, a plurality of sources of ringing current, means for connecting a.

different source of ringing current with each set of said arms,-a calling device, and automatic means for connecting the calling device with the connector for operating the same.

29. In a telephone system, a subscribers line, a connector switch for connecting with ,said.line,said switch including'a plurality of sets of armsfor connecting with the line, a plurality of sources of ringing, current, a pluralit of relays, means controlled by said relays or connecting a difl'erent' source of ringing current with each set of said arms, a calling device, and automatic means for connecting the calling device with the connector for operating the same.

30. In a telephone system, a subscribers line, a connector switch for connecting with said line, said switch including a plurality of banks of; contacts, a plurality of arms adapted to engage with each of said banks, said arms being angularly displaced whereby one of said arms leaves the last contact of a bank as: the next of said arms engages the first contact, a plurality of sources of (ringing current, means for connecting a different source of ringing current with each arm, associated with a bank of contacts, a calling' device, and automatic means for" connecting the calling device with the connector for operating the same.

31. In a telephone system, a subscriber s line, a connector switch for connecting with said line, means associated with the connector for applying ringing current to the said line, said means including a plurality of-relays, means controlled by each of said relays for connecting a separate source of ringing current with said line, means for energizing said relays simultaneously and applying ringing current to the line, a calling devlce, and automatic means for connecting the calling device with the connector" 

